Poly(aliphatic ester-carbonate)s are high flow, ductile materials that are particularly useful in manufacturing articles by injection molding. Poly(aliphatic ester-carbonate)s are generally manufactured from aliphatic dicarboxylic acid and bisphenol comonomers, and a carbonyl source by a two-stage interfacial process. A strong alkali base is present to aid dissolution of the comonomers in the two-phase reaction medium, and the carbonyl source is introduced in two stages, a first lower pH stage, followed by a second, higher pH stage. There remains a need in the art, however, for improved methods for the manufacture of poly(aliphatic ester-carbonate)s, particularly methods that can produce copolymer with high throughput. It would be useful if the methods could be adapted to produce poly(aliphatic ester-carbonate)s having one or more new or improved properties, such as improved hydrostability.